Help converting a recipe.

[jbush_13]

Hey guys this is an American amber ale recipe from northern brewer for 5 gallons. Could someone help me convert this to a four gallon recipe? Also do you suggest mashing for 60 or 90 minutes. I'm doing a biab sparge method. Thanks!


O.G: 1.047 READY: 6 WEEKS Suggested fermentation schedule: -- 1–2-weeks-primary;-1–2-weeks-secondary;-
2-weeks-bottle-conditioning-
MASH INGREDIENTS
-- 6.5-lbs-Rahr-2-row-Pale- -- 2-lb-German-Munich-Malt- -- 1-lb-Caramel-60-
BOIL ADDITIONS & TIMES
-- 1.5-oz.-Cascade-(60-min)- -- 1-oz.-Cascade-(1-min)-
YEAST
-- DRY YEAST (DEFAULT): Safale-US-05-Ale-Yeast.-- Optimum-temp:-59°–75°-F
PRIMING SUGAR
-- 5-oz-Priming-Sugar-(save-for-Bottling-Day)-
MASH SCHEDULE: SINGLE INFUSION
Sacch’ Rest: 153° F for 60 minutes Mashout: 170° F for 10 minutes
BOIL ADDITIONS & TIMES
1.5 oz. Cascade (60 min) 1 oz. Cascade (1 min)
YEAST
DRY YEAST (DEFAULT):
Safale US-05 Ale Yeast. Optimum temp: 59°–75° F

 

[chickypad]

If your efficiency matches that of the recipe (eyeballing it looks like about 70%) then you can pretty much just multiply everything by 0.8. If you don't know your efficiency that's probably a good enough starting point. Hops would also get multiplied by 0.8, then just add the whole packet of yeast. I would encourage you to keep good measurements then in the future you can adjust any recipe to your batch size and efficiency. Software or a calculator can help with the numbers. I use Beersmith but I also find Brewer's friend pretty good. Most mashes are probably done well before 60 min, though many of us use that as our default. 90 min is overkill.

 

[jbush_13]

I believe the F.G is supose to be 1.017.

 

[chickypad]

That sounds pretty high for a 1.047 beer with US-05, I suspect it will finish lower. The FG tells you the attenuation. You measure your OG to figure out what your efficiency was (i.e. how well you converted the starches into sugars in your mash and how well you collected those sugars).

 

[jbush_13]

Oh I'm sorry I meant 1.007.

 

[jbush_13]

How can out tell the efficieny just by looking? Also do you suggest a mashout?

 

[chickypad]

How can out tell the efficieny just by looking? Also do you suggest a mashout?

The grainbill is 9.5 lbs. Averaging 36 ppg (that's an oversimplification but close enough for these purposes) 100% efficiency would be 342 gravity pts. The recipe is 1.047, 47 x 5 gal = 235 gravity pts. 235/342 = 69% efficiency.

I never do a mashout unless fly sparging.

 

[jbush_13]

How did you come up with the 36 ppl value?

 

[chickypad]

How did you come up with the 36 ppl value?

Most base malts are in the 35-37 ppg range, so I often use 36 ppg as an average for figuring quick calculations. To do it properly you would multiply the weight of each grain by it's potential from a chart or malt analysis sheet, then add them up - or go the easier route of plugging into software or a calculator. Here are a couple malt charts for reference:

Beersmith
HBT wiki